, J:  ( 


I 


LI3RARY 


OF  THE 


NiVERSITY  of  ILLINOIS. 


THE  GLACIAL  DEPOSITS  OF  INDIANA, 


BY 


FRANK  LEVERETT, 


J 


OF  THE 


U.  S.  Geological  Survey. 


i 


i 


, . ..  . , , WwtfjSbJL 


Tiik  Inland  Educator 


23 


fire.”  Many  a good  flint  is  useless,  because  no 
friction  is  applied. 

i / We  have  recognized  that  poetry  excites  images 
by  addressing  i'self  to  the  imagination  and  mem- 
pry,  and  therefore  aids  in  psychic  action,  and  it 
occupies  its  legitimate  place.  But  the  remaining 
.■wo-thhds  of  this  circle  of  beauty,  have  been  put 
aside  as  non-essential. 

Mr.  Butterworth,  well-known  as  the  editor  of 
die  “ Youth's  Companion ,”  quoted  recently  and 
with  much  emphasis  to  a body  of  educators — 
“Learn,  not  how  to  get  a living,  but  how  to  lire." 
When  this  idea  becomes  the  prevalent  one,  and 
the  fact  that  fifty  cents  per  day  will  keep  your 
physical  self  in  good  condition,  while  the  entire 
material  universe  is  not  sufficient  nurture  for  the 
mental  body — it  will  then  be  recognized  that 
those  studies  which  teach  “how  lo  live”  will  be 
as  essential  as  are  those  which  teach  us  “howto 
get  a living.”  Poetry,  art,  and  music  are  all  rec- 
ognized as  avenues  leading  to  larger  realms, — as 
the  “Jacob’s  Ladder”  by  which  a higher  intellec- 
tual atmosphere  is  reached : but  because  of  its 
more  immediate  connection  with  sensation,  music, 
may  be  rightfully  regarded  as  the  more  universal, 
the  more  powerful  of  the  three. 

In  poetry,  painting,  or  sculpture,  intervening 
act  or  acts,  are  necessary  before  the  elements  are 
appreciated  by  sensation,  while  in  music,  the  sen- 
sations of  tone  are  the  material  of  the  art.  Because 
of  this  union,  music  deals  more  intimately  with 
the  emotions,  than  any  other  educational  factor, 
and  thus  becomes  an  ethical  force.  Not  only  so, 
but  the  psychic  processes  which  a well-directed 
lesson  in  music  causes,  exceed  in  number  and 
power  those  caused  bv  almost  any  two  recitations 
of  any  other  branches;  and,  added  to  this,  the 
study  itself  lifts  these  processes  out  of  the  “peda- 
gogical rut,”  and  wraps  around  them  its  own  in- 
comparable beauty. 

Are  not  those  who  hold  the  affairs  educational 
in  their  grasp — who  hesitate  to  place  these  phases 
of  education  before  the  child,  depriving  him  of  a 
heritage  that  is  priceless?  And  is  not  this  legiti- 
mate part  of  every  training  eyed  askance,  mainly 
because  of  the  burden  of  opposition  which  the  un- 
knowing, unthinking  public  would  cause  the  lead- 
ers of  such  a movement  to  bear? 

There  is  an  ancient  legend  which  would  just 
here  be  apropos.  It  runs  like  this  : — “ When  birds 
were  first  formed  they  were  created  without 
wings.  They  lived  this  way  for  a long  time, 
gathering  their  food  and  journeying  in  a slow 
troublesome  way.  Finally,  as  if  this  mode  of  life 
were  not  hard  enough,  God  placed  a little  burden 
across  their  backs,  and  said,  ‘I  wish  you  to  carry 
this  for  me.’  This  they  did  also  for  a long  time 


cheerfully  and  uncomplainingly,  and  because  of 
the  spirit  with  which  the  burden  was  borne — it 
was  given  to  them  forever,  but  changed — into 
wings.” 

If  this  burden  (if  it  seems  so)  of  placing  before 
children  suggestions  of  their  better,  higher  nature 
be  borne  in  the  spirit  of  justice  to  the  minds  to  be 
educated,  it  will  be  changed  into  wings  for  all. 

Bella  Pakk. 

Franklin,  Ind. 

Site  Considered  tite  Ltey. 

At  a Teachers’  Convention  in  Detroit,  lately,  a 
lady  speaking  about  the  influence  of  beautiful 
objects  upon  the  character  and  conduct  of  young 
pupils,  told  a pretty  story  received  by  her  from  an 
eye-witness,  and  thus  reported  by  the  News  Tribune. 
The  occurrence  took  place  in  New  York. 

“ Into  a school  made  up  chiefly  of  children  from 
the  slums  the  teacher  one  day  carried  a beautiful 
cal  la  lily.  Of  course  the  children  gathered  about 
the  pure,  waxy  blossom  in  great  delight. 

“One  of  them  was  a little  girl,  a waif  of  the 
streets,  who  had  no  care  bestowed  upon  her,  as 
was  evinced  by  the  dirty,  ragged  condition  she 
was  always  in.  Not  only  was  her  clothing  dread- 
fully soiled,  but  her  face  and  hands  seemed  totally 
unacquainted  with  soap  and  water. 

“As  this  little  one  drew  near  the  lovely  flower, 
she  suddenly  turned  and  ran  away  down  the  stairs 
and  out  of  the  building.  In  a few  minutes  she 
returned  with  her  hands  washed  perfectly  clean, 
and  pushed  her  way  up  to  the  flower,  where  she 
stood  and  admired  it  with  intense  satisfaction. 

“It  would  seem,”  continued  Miss  Coffin,  “that 
when  the  child  saw  the  lil  v in  its  white  purity,  she 
suddenly  realized  that  she  was  not  lit  to  come  into 
its  atmosphere,  and  the  little  thing  fled  away  to 
make  herself  suitable  for  such  companionship. 
Did  not  this  have  an  elevating,  refining  effect  on 
the  child?  Let  us  gather  all  the  beauty  we  can 
into  the  school-room.” — The  Youth's  Companion. 

No.  Freedom  has  a thousand  charms  to  show, 
That  slaves,  howe’er  contented,  never  know. 

* * * «■  * * * « 

Religion,  virtue,  truth,  wlmte’er  we  call 
A blessing — Freedom  is  the  pledge  of  all. 

Cow  per — Table  Tall:. 


For  murder,  though  it  have  no  tongue,  will  speak 
With  most  miraculous  organ. 

Sha  KESI’E.UIE. — Hamlet. 


24 


The  Inland  Educator 


SCIENCE. 


Conducted  by  Charles  Ii.  Dryer. 


“ To  read  a statement  of  a fact  (jives  knowledge;  to  ver- 
ify the  fact  gives  training ; to  discover  it  gives  inspira- 
tion. Training  and  inspiration,  not  the  facts  them- 
selves, are  the  justification  of  science  teaching .” 


Studies  in  Indiana  Geography.— IV. 


The  Glacial  Deposits  of  Indiana. 


By  Frank  Leverett  of  the  r.  S.  Geological  Survey. 


Note  Concerning  the  Glacial  Boundary.  The  glacial  map  of 
Indiana  which  is  here  presented,  was  prepared  in  March,  1896, 
and  the  position  of  the  glacial  boundary  in  Southeastern 
Indiana  and  adjacent  portions  of  Kentucky,  was  based 
mainly  upon  a map  prepared  by  Prof.  G F.  Wright,  for  his 
official  report  (U.  S.  Geol  Survey,  Bui.  No.  58,  1890,  p.  05). 
In  the  month  of  June,  1890,  the  writer  examined  the  imme- 
diate borders  of  the  Ohio  valley  from  near  Louisville  up  to 
Maysville,  Kentucky,  and  found  that  the  glaciation  extended 
to  the  Ohio  river  throughout  this  distance,  nearly  200  miles, 
except  perhaps  for  a few  miles  below  Maysville.  In  several 
places  till  was  found  in  considerable  amount  south  of  the 
Ohio,  not  only  in  the  bond  of  the  Ohio  opposite  Cincinnati, 
where  it  had  been  noted  by  Prof.  Wright  and  others,  but  also 
at  numerous  points  both  above  and  below  this  bend.  The 
full  extent  of  glaciation  and  the  position  of  the  glacial  boun- 
dary in  Northern  Kentucky  has  not,  however,  been  deter- 
mined, nor  lias  further  study  been  given  the  boundary 
westward  from  Louisville.  There  seems  to  be  a general 
agreement  among  the  several  geologists  who  have  worked  in 
Southern  Indiana,  that  an  unglaciated  district  extends  from 
the  Ohio  river  northward  as  far  as  Northern  Monroe  county, 
but  the  full  extent  of  this  unglaciated  district  has  not  been 
determined.  The  glacial  boundary  as  laid  down  on  this 
map  should,  therefore,  be  considered  as,  at  best,  only  a rude 
approximation. 

introductory. 

In  Indiana,  the  glacial  deposits  and  scorings 
have  been  recognized  from  the  earliest  days  of  set- 
tlement; indeed,  it  is  in  this  state  that  we  find 
about  the  first  recognition  in  America  of  the  bowl- 
ders as  erratics  and  of  strife  as  products  of  ice 
action.  So  long  ago  as  1828,  granite  and  other  rocks 
of  distant  derivation  were  observed  by  geologists 
near  New  Harmony,  in  the  southwestern  part  of 
the  state.*  At  nearly  as  early  a date  (1842),  strife 
were  noted  near  Richmond,  in  the  eastern  part  of 
the  state,  f 

Notwithstanding  the  early  date  at  which  obser- 
vations of  glacial  action  began,  very  little  attention 
was  given  to  the  drift,  here  or  elsewhere,  until 
within  the  past  twenty  years.  It  was  commonly 
passed  over  in  geological  reports  much  as  the  soil 

*See  Geology  of  Indiana,  1878,  pp.  105-106. 

|See  Araer.  Jour.  Sci.,  Vol.  XL1V,  1842-3,  pp.  281-313. 


is  even  to-day,  with  some  casual  remark  concerning 
its  presence  in  great  or  small  amount.  Within  the 
past  twenty  years  interest  in  these  deposits,  be- 
cause of  the  varied  history  which  they  reveal,  has 
been  so  aroused,  that  many  geologists,  both  in 
America  and  Europe  are  making  a systematic 
study  of  them. 

In  Indiana,  these  deposits  are  engaging  the  atten- 
tion of  both  the  State  and  the  United  States  Sur- 
vey. The  study  of  general  features  and  a com- 
parative study  of  the  drift  of  Indiana  and  neigh- 
boring states  has  been  undertaken  by  the  United 
States  Survey,  while  the  detailed  examination  of 
deposits  has  been  entered  upon  by  the  State  Sur- 
vey. Professor  T.  C.  Chamberlin  lias  superin- 
tended the  United  States  Survey  work  and  has  him- 
self silent  considerable  time  in  Northern  and  West- 
ern Indiana.  Under  his  direction  Professor  G.  F. 
Wright  and  Professor  J.  C.  Branner,  have  investi- 
gated the  glacial  boundary;  Professor  L.  C.  Woos- 
ter has  studied  the  district  north  of  the  Kankakee, 
and  t he  writer  has  made  a reconnoissance  of  nearly 
all  the  drift-covered  part  of  the  state.  Professor 
Wright’s  results  have  already  been  published  in 
United  States  Geological  Survey  Bulletin,  No.  58, 
issued  in  1890.  Professor  Chamberlin’s  earlier 
results  are  set  forth  in  his  paper  on  the  Termi- 
nal Moraine,  in  the  Third  Annual  Report  of  the 
United  States  Geological  Survey  for  1S81-82.  The 
later  results  of  his  studies  and  those  of  Professors 
Branner,  Wooster  and  the  writer,  are  largely 
unpublished.  Through  the  courtesy  of  Professor 
Chamberlin  the  writer  is  permitted  to  set  forth 
some  of  the  leading  results  in  this  paper. 

The  work  of  the  State  Survey  has  not  been  uni- 
form. Portions  of  it  have  been  less  detailed  than 
that  of  the  United  States  Survey,  while  other  por- 
tions have  been  carried  into  greater  detail.  Proba- 
bly the  most  detailed  and  careful  study  of  any  con- 
siderable area  is  that  made  by  Dr.  C.  R.  Drver  in 
the  northeastern  part  of  the  state.*  An  examina- 
tion of  the  reports  of  t he  Indiana  Geological  Survey 
will  serve  to  set  forth  these  differences  and  to  show 
the  importance  of  extending  the  detailed  study  of 
glacial  deposits  over  all  the  glaciated  portions  of 
the  state.  Such  a study  probably  can  be  carried  on 
to  the  best  advantage  under  the  organization  of  a 
State  Survey.  But  independent  workers  can  do 
much  to  throw  light  on  these  deposits  by  collect- 
ing the  records  of  well-borings  and  by  careful  notes 
taken  at  natural  or  artificial  exposures. 

Before  entering  upon  the  discussion  of  the  Indi- 
ana drift  a few  words  of  explanation  seem  neces- 
sary concerning  the  material  of  the  drift,  and  con- 
cerning the  gathering  grounds  of  the  ice  which 

*See  sixteenth,  seventeenth  and  eighteenth  reports  of 
State  Geologist. 


Tin:  lx  land  Educator 


26 


overspread  this  region.  The  latter  subject,  how- 
ever, has  been  so  well  covered  by  Mr.  Taylor  that 
but  little  need  be  added. 

MATERIALS  OK  THE  DRIFT. 

It  is  quite  a prevalent  idea  that  the  bowlders 
which  strew  the  surface  of  the  glaciated  districts 
C and  which  have  suffered  a transportation  from 
distant  regions,  constitute  the  most  impressive 
evidence  of  ice  action.  It  seems  by  many  not  to 
be  understood  t hat  the  thick  deposits  of  stony  clay 
with  associated  beds  of  sand  and  gravel  which 
blanket  the  North  Central  States  to  a depth  of  1(K), 
200  feet,  and  occasionally  500  feet,  are  also  due  to 
ice  transportation.  Over  a large  part  of  the, coun- 
try from  the  Dakotas  eastward  to  the  Appalachian 
ranges,  these  deposits  arc  so  thick  that  ordinary 
wells  fail  to  reach  their  bottom,  and  many  of  the 
valleys  of  the  large  streams  are  formed  entirely  in 
them.  The  bowlders  in  reality  constitute  but  an 
i/ insignificant  portion,  for  probably  ninety-five,  per 
cent,  of  the  drift  of  these  states  consists  of  minute 
rock  fragments  and  sand  and  clay,  and  of  the 
remaining  five  per  cent,  only  a small  part  is  made 
up  of  large  blocks  of  distant  derivation;  •/.  e.,  of 
bowlders  proper. 

An  examination  of  rocks  in  the  drift  mass  will 
usually  disclose  a large  percentage  of  material 
which  has  not  been  transported  far,  but  there  is 
usually  to  be  found  a Sprinkling  of  rocks  from  dis- 
tant localities.  Let  the  reader  select  some  space, 
sav  a square  yard,  in  a gravel  pit  or  other  exposure 
and  set  about  classifying  the  several  kinds  of  rocks 
represented,  and  he  will  ascertain  the  relative 
amount  of  local  and  distant  material. 

(/  In  its  bedding  the  drift  displays  great  irregu- 
larity. In  general,  it  consists  of  a confused  mass 
of  angular,  semi-angular,  and  well-rounded  stones 
imbedded  in  a matrix  of  sandy  clay.  This  confused 
mass  was  named  till  by  Scottish  geologists,  and  this 
term  has  been  adopted  by  American  geologists. 
By  some  it  is  called  bowlder  clay  because  of  its 
containing  bowlders.  With  the  till  one  can  find, 
in  many  exposures,  beds  or  pockets  of  sand  and 
gravel.  These  beds  in  some  cases  comprise  the 
entire  section,  but  they  are  usually  subordinate  to 
the  till. 

In  some  parts  of  the  glaciated  districts  the  till 
j / constitutes  the  lower  part  of  the  drift,  while  the 
sand  and  gravel  lie  mainly  near  the  surface.  In 
Indiana  such  a relationship  does  not  prevail  over 
wide  areas.  The  drift  deposits  of  this  state  are 
unusually  varied  in  the  arrangements  of  till  sheets, 
gravel  beds  and  sand  beds ; what  is  true  of  one 
township  may  find  no  application  in  a neighboring 
one. 

‘■•Inland  Educator,  Yol  II  , pi>.  ioa,  138. 


Farther  on  we  shall  discuss  the  evidence  upon 
which  is  based  the  conclusion  that  there  are  in 
Indiana  drift-sheets  differing  widely  in  age. 

GLACIATED  ROCK  SURFACES. 

The  peculiar  appearances  presented  by  rock  sur- 
faces which  have  been  abraded  by  the  ice-slieet 
are  usually  of  such  a striking  nature  as  to  arrest 
the  attention  of  untrained  as  well  as  of  trained  ob- 
servers. These  surfaces  differ  somewhat  from  place 
to  place  but  still  have  a characteristic  appearance. 
They  present,  usually,  a series  of  parallel  or  but 
y slightly  divergent  lines  or  grooves,  varying  in  size 
from  faint  scratches  as  fine  as  a hair,  to  broad 
shallow  grooves  an  inch  or  two,  and  occasionally 
several  inches  in  widt  h.  Between  the  grooves  the 
rock  has  usually  been  scoured  down  to  a plane 
surface.  The  stria-  indicate,  as  a rule,  the  general 
course  of  ice-movement  and  with  few  exceptions 
point  toward  the  margin  presented  by  the  ice- 
sheet  at  the  time  they  were  formed. 

As  the  ice-sheet  was  subject  at  times  to  excessive  I 
wastage,  if  not  to  complete  destruction,  followed 
by  readvance  in  which  some  shifting  of  movement 
ip  occurred,  we  find  the  striae  showing  some  interest- 
ing variations  in  neighboring  localities.  Some  of 
the  best  illustrations  in  America  are  to  be  found 
in  Western  I ndiana  and  these  are  discussed  farther 
on. 

TIIE  GLACIAL  GATHERING  GROUNDS. 

On  the  glacial  map  of  North  America  are  shown 
the  extent  of  glaciation,  and  the  several  main  cen- 
ters of  dispersion;  viz.,  the  Cordilleran,  Keewatin, 
Labrador,  and  Greenland.  The  glaciated  districts 
in  North  America  are  estimated  to  cover  4,tKX),(KK) 
square  miles.  It  is  doubtful,  however,  if  this  en- 
tire area  was  covered  by  the  ice-sheet  at  any  one 
time.  Dr.  G.  51.  Dawson,  director  of  the  Canadian 
Geological  Survey,  has  found  evidence  that  the 
Cordilleran  ice-field  overspread  the  Rocky  Moun- 
tains and  extended  some  distance  to  the  east  and 
then  withdrew  before  the  Keewatin  ice-sheet  had 
reached  that  region  *. 

Similarly  the  Keewatin  ice-sheet  culminated  and 
wit  hdrew  from  its  southern  limits  ( in  Missouri  and 
Iowa)  before  the  Labrador  ice-field  had  reached 
its  extreme  western  limits.  The  writer  has  found 
that  the  Labrador  movement  extended  into  South- 
eastern Iowa  at  a date  considerably  later  than  the 
time  when  the  Keewatin  ice-sheet  withdrew;  there 
being  a sril  and  other  evidences  of  an  ''nterval 
found  on  the  surface  of  the  Keewa*  -1  drift  and 
under  the  drift  of  the  Labrador  s=l  et-  !*■  should 
be  understood,  however,  that  tb  Auction  in  size 
of  the  Cordilleran  and  Keew  -sheets  at  the  time 
of  the  culmination  of  tb  'L,a  1J  01  sheet,  may 

# Bulletin  of  the  Geol.  Soc’p  Vl"Lriva,  \ ol.  A II.  pp.  _> 

November,  1S95 


Titt:  Itstuand  Educator. 


27 


have  amounted  to  but  a small  percentage  of  the 
area  which  they  had  covered. 

Greenland  is  now  ice-covered  while  districts  to 
the  west  which  have  been  ice-covered  are  nearly 
free  from  glaciers.  The  continuation  of  glaciation 
there  parallels  the  observations  in  the  fields  to  the 
west  and  adds  to  the  weight  of  these  observations 
in  indicating  a progressive  culmination  of  the  ice- 
sheet  from  west  to  east. 

Aside  from  the  four  main  gathering  grounds  there 
appear  to  have  been  minor  gathering  grounds  in 
the  extreme  east  on  New  Brunswick  and  on  Nova 
Scotia  as  indicated  by  Mr.  Robert  Chalmers  in  his 
paper  in  the  Annual  Report  of  the  Canadian  Sur- 
vey for  1894.  There  were  also  small  ice-fields  on 
the  Rocky  and  Sierra  Nevada  Mountains  in  the 
Western  United  States,  as  described  many  years 
ago  by  King,  Whitney  and  others. 

THE  GLACIAL  SUCCESSION  IN  INDIANA. 

First  Tee  Invasion.  This  state  was  invaded  by  ice 
which  had  as  its  center  of  dispersion  the  elevated 
districts  to  the  east  and  south  of  Hudson  Bay. 
There  was  a movement  from  the  region  north  of 
Lake  Huron  in  a course  west  of  south  over  the 
Lake  Michigan  basin,  Illinois  and  Western  Indiana. 
There  was  also  a southward  movement  from  the 
same  region  across  Lakes  Huron  and  Erie,  Western 
Ohio  and  Eastern  Indiana.  It  is  not  known  whether 
these  movements  were  independent  and  of  differ- 
ent dates  or  whether  there  was  simply  a radiation 
in  movement  of  a single  ice  accumulation.  It 
should  not  be  taken  for  granted  that  even  within 
the  state  of  Indiana  the  ice-sheet  was  occupying  the 
glacial  boundary  completely  at  any  one  time. 

The  ice  deposited  but  little  drift  near  its  extreme 
limits,  either  in  Indiana  or  states  to  the  west. 
There  is  not,  as  a rule,  a Avell  defined  ridge  or  thick 
belt  of  drift  along  the  glacial  boundary,  such  as 
characterizes  the  southern  limit  of  some  of  the 
later  drift-sheets,  though  occasional  ridging  of 
drift  is  to  be  seen,  as  in  Chestnut  Ridge  in  Jackson 
county*  and  a similar  ridge  in  Southern  Morgan 
county.  The  boundary  of  the  drift  in  Indiana  is 
usually  so  vague  and  ill  defined  that  it  is  only 
approximately  known.  (See  note  accompanying 
Glacial  Map  of  Indiana.) 

If  we  may  judge  of  the  deposit  over  the  state 
from  the  outlying  portions,  south  of  deposits  made 
by  later  invasions,  the  deposits  of  the  first  invasion 
are  of  much  less  volume  than  those  of  later  inva- 
sions. They  appear  to  include  not  more  than  30 
of  the  130  feet  which  the  writer  estimates  the  state 
to  carry.  In  the  portion  of  the  state  which  was 
glaciated  but  once  the  thickness  is  usually  less  than 
25  feet,  but  filled  valleys  will  probably  give  it  an 
average  somewhat  above  that  amount.  What  is 

* Geology  of  Indiana,  1871,  pp.  56-57. 


true  of  the  drift  of  the  earliest  invasion  in  South- 
ern Indiana  is  true  also  of  the  same  drift  of  South- 
ern Illinois  and  Southwestern  Ohio.  This  invasion 
seems,  therefore,  to  be  quite  widely  characterized 
by  a lighter  deposition  than  that  of  later  invasions. 

First  Interglacial  Interval.  After  reaching  the 
line  marked  by  the  glacial  boundary,  the  ice  melted 
away  and  left  the  drift  exposed  to  atmospheric 
agencies.  How  far  to  the  north  the  land  became 
uncovered  is  not  known.  At  this  time  a black  soil 
was  formed,  which  is  now  concealed  beneath  depos- 
its of  silt,  termed  loess,  in  Southern  Indiana,  and  be- 
neath later  deposits  of  till  in  the  northern  portion 
of  the  state.  This  soil  is  found  at  the  base  of  the 
loess  at  various  points  over  the  southern  portions 
of  the  state,  but  is  best  developed  on  flat  tracts. 
It  may  be  seen  beneath  the  loess  in  the  flat  dis- 
tricts east  and  south  of  Terre  Haute  at  a depth  of 
from  six  to  eight  feet.  The  vegetable  matter  appears 
to  have  accumulated  there  just  as  it  does  on  the 
present  surface  of  poorly  drained  tracts  in  northern 
latitudes,  where  decay  is  slower  than  accumulation. 
In  Western  Indiana,  from  Parke  and  Vermillion 
counties  northward,  the  soil  is  found  below  a later 
sheet  of  till  at  depths  varying  from  twenty  feet  up 
to  one  hundred  feet  or  more.  Numerous  references 
to  the  soil  below  till  in  this  portion  of  the  state 
are  to  be  found  in  the  Indiana  Geological  Reports. 
It  has  not  been  observed  in  Eastern  Indiana,  so  far 
as  the  writer  is  aware,  but  may  be  present,  for  few 
valleys  there  reach  low  enough  to  expose  it.  It 
seems  not  to  be  so  conspicuous,  however,  as  in 
Western  Indiana,  otherwise  it  would  have  been 
brought  to  notice  in  well-borings. 

No  conclusions  have  been  reached  concerning 
the  length  of  time  involved  in  the  formation  of 
this  soil.  The  land  at  that  time  seems  to  hav^e 
been  so  low  or  so  flat  in  Indiana,  that  drainage 
lines  were  not  well  developed  in  the  drift  surface, 
and  we  are  thus  deprived  of  one  important  means 
of  estimating  the  work  accomplished. 

Main  Loess  Depositing  Stage.  Loess  is  a term 
applied  to  a fine-grained  yellowish  silt  or  loam, 
which  overspreads  the  southern  portion  of  the 
glacial  drift  in  North  America,  and  extends  thence 
southward  on  the  borders  of  the  Mississippi  valley 
to  the  shores  of  the  Gulf  of  Mexico.  The  term  was 
originally  applied  to  deposits  of  this  character  on 
the  Rhine,  which  have  very  extensive  development 
in  the  German  lowlands  and  bordering  districts  in 
Northern  Europe.  Microscopical  analysis  shows 
it  to  consist  principally  of  quartz  grains,  but  it 
usually  has  a variety  of  other  minerals  such  as 
occur  in  the  glacial  drift.  It  is  apparently  derived 
from  the  drift,  either  by  the  action  of  water  or 
wind.  In  many  places,  especially  on  the  borders 
of  the  large  valleys,  the  loess  is  charged  with  cal- 


28 


Tiie  Tnxand  Educator. 


careous  matter  which  partially  cements  it.  When 
excavations  are  made  in  it  the  banks  will  stand 
for  years,  and  will  retain  inscriptions  nearly  as  well 
as  the  more  consolidated  rock  formations.  It  has 
a strong  tendency  to  vertical  cleavage,  and  usually 
presents  nearly  perpendicular  banks  on  the  bor- 
ders of  streams  which  erode  it.  It  often  contains 
concretions  or  irregular  nodules  of  lime  and  of  iron 
and  manganese  oxides.  It  is  also  often  highly  fos-  j 
siliferous.  The  fossils  are  usually  land  and  fresh- 
water mollusks,  but  occasionally,  insects  and  bones 
of  mammals  are  found. 

The  deposit  appears  to  be  mainly  of  one  stage  in 
the  glacial  period,  and  has  been  definitely  corre- 
lated by  Mr.  W.  J.  McGee  with  an  ice  invasion 
which  followed  the  interglacial  stage  just  dis- 
cussed.* In  the  region  which  Mr.  McGee  studied, 
in  Northeastern  Iowa,  it  connects  on  the  north 
with  a sheet  of  till  called  by  him  the  upper  till, 
and  afterwards  named  by  Professor  Chamberlin, 
the  Iowan  Drift-Sheet.  The  writer  has  visited  that 
region  and  fully  concurs  with  Mr.  McGee’s  opinion. 
This  drift-sheet  has  not  been  recognized  in  Indiana, 
for  if  present  it  lies  entirely  within  the  limits  of  a 
later  invasion  and  the  later  deposits  have  con- 
cealed it. 

There  is,  in  Western  Indiana  along  the  Wabash,  a 
loess  of  more  recent  date  than  the  main  deposit, 
but  it  is  confined  to  low  altitudes,  seldom  appearing 
more  than  one  hundred  feet  above  the  river  level. 
In  Western  Illinois,  a loess  has  been  found  which 
is  older  than  the  main  deposits,  but  it  has  been 
seen  in  only  a few  places  and  is  apparently  a thin 
and  perhaps  patchy  deposit.  It  is  thought  by  Pro- 
fessor Salisbury  that  the  loess  of  the  lower  Missis- 
sippi was  deposited  at  two  distinct  stages.  Loess 
is,  therefore,  a deposit  which,  like  sand  or  gravel, 
may  be  laid  down  whenever  conditions  are  favor- 
able, but  the  great  bulk  of  it  having  been  deposited 
at  a definite  stage  of  the  glacial  period,  it  seems 
proper  to  refer  to  that  stage  as  the  Loess  stage. 

In  Southern  Indiana,  and  in  bordering  portions 
of  Southern  Ohio  and  Southern  Illinois,  there  is  a 
continuous  sheet  of  pale  silt  locally  termed  “ white 
clay,  ” which  is  thought  to  be  a phase  of  the  loess, 
though  more  clayey  and  less  uniform  in  texture 
than  typical  loess.  It  covers  the  interfluvial  tracts 
as  far  north  as  the  limits  of  a later  sheet  of  drift, 
and  has  been  discovered  at  a few  places  beneath 
that  later  drift.  It  probably  extended  much  farther 
north  than  its  present  exposed  limits,  for  the  ice- 
sheet  appears  to'  have  receded  far  to  the  North  at 
the  main  loess-depositing  stage,  thus  leaving  the 
surface  free  to  receive  these  deposits.  The  north- 
ern limit  of  the  exposed  portion  in  Indiana  is  j 

-Eleventh  Annual  Report,  U.  S.  Geol.  Survey  1SS9-90,  pp 
435-471. 


marked  by  the  “ Wisconsin  boundary,”  shown  on 
the  Glacial  Slap  of  Indiana.  This  deposit  is 
usually  but  a few  feet  in  thickness,  seldom  exceed- 
ing eight  feet.  Along  the  Wabash,  however,  where 
it  becomes  a typical  loess  it  often  reaches  a thick- 
ness of  twenty  to  twenty-five  feet.  It  may  be  readily 
distinguished  from  the  underlying  till  both  by  tex- 
ture and  color.  It  contains  only  very  minute  rock 
fragments,  while  the  till  is  thickly  set  with  stones 
of  all  sizes.  In  color  it  is  paler  yellow  than  the  till. 
There  is  usually,  also,  a weathered  zone  at  the  top  of 
the  till  and  sometimes  a black  soil,  making  still 
more  clear  the  line  of  contact. 

The  loess  and  its  associated  silts  is  found  at  all 
altitudes  in  Southern  Indiana  ; from  the  low  tracts 
near  the  Wabash,  scarcely  400  feet  A.  T.,  up  to  the 
most  elevated  tracts  in  Southeastern  Indiana, 
which  in  places  exceed  1,000  feet  A.  T.  The  great 
range  in  altitude  is  one  of  the  most  puzzling  feat- 
ures of  the  loess.  The  same  perplexing  distribu- 
tion is  found  in  Europe  as  in  America.  As  yet,  no 
satisfactory  solution  for  the  problem  of  its  deposi- 
tion at  such  widely  different  altitudes  has  been 
found. 

Interglacial  Stage  Following  the  Loess  Depos'tion. 
Between  the  main  deposition  of  loess  and  the  in- 
vasion of  Northern  Indiana  by  a later  ice-sheet, 
considerable  time  elapsed ; for  we  find  that  the 
drainage  lines  have  reached  a much  more  advanced 
stage  on  the  loess-covered  districts  south  of  the 
deposits  of  the  later  ice-sheets  than  they  have  upon 
those  deposits.  It  is  found  that  large  valleys  had 
been  opened  in  the  loess  and  the  underlying  drift 
before  the  streams  from  the  later  ice-sheet  brought 
their  deposits  into  the  valleys.  This  interval  of  val- 
ley-erosion is  thought  by  several  who  have  had  op- 
portunity to  study  it,  including  the  present  writer, 
to  be  longer  than  the  time  which  has  elapsed 
since  the  ice-sheet  last  occupied  Northern  Indiana. 

The  question  has  been  raised,  whether  the  greater 
amount  of  erosion  outside  the  later  drift  may  not 
have  been  due  to  streams  of  large  volume  which 
accompanied  the  later  ice  invasion.  That  this  is 
only  a minor  influence,  is  shown  by  the  fact  that 
valleys  in  Southern  Illinois  which  lie  entirely  out- 
side the  reach  of  such  waters  are  much  larger  than 
valleys  of  similar  drainage  areas  within  the  limits 
of  the  later  drift-sheet. 

It  cannot  be  urged  that  the  region  with  the 
smaller  valleys  is  less  favored  by  slopes  or  stream 
gradients  than  the  region  with  well-developed 
valleys,  for  the  reverse  is  the  case.  There  are  large 
areas  within  the  loess-covered  districts  which  do 
not  possess  the  reliefs  and  other  conditions  favora- 
ble for  the  rapid  development  of  drainage  lines 
which  appear  in  much  of  the  newer  drift.  In  short, 
there  appears  no  escape  from  the  view,  that  the 


\ 


)/ 


80 


The  J^ixand  Educator. 


interval  between  the  loess  deposition  and  the  later 
ice  invasion  was  a long  one. 

The  yV'ixcomin  Stage  of  Glaciation.  After  the  in- 
terglacial interval  just  mentioned,  there  occurred 
one  of  the  most  important  stages  of  glaciation  in 
the  entire  glacial  period.  It  is  marked  by  heavier 
deposits  of  drift  than  those  made  at  any  other 
invasion.  Throughout  much  of  its  southern  boun- 
dary in  the -United  States,  a prominent  ridge  of 
drift  is  to  be  seen  rising  in  places  to  a height  of  100 
feet  or  more  above  the  outlying  districts  on  the 
south,  and  merging  into  plains  of  drift  on  the  north 
which  are  nearly  as  elevated  as  its  crest. 

At  this  time  the  ice  reached  its  farthest  exten- 
sion in  New  England,  and  also  in  much  of  the  dis- 
trict between  New  England  and  the  Scioto  River  in 
Ohio.  From  the  Scioto  westward,  however,  it 
usually  fell  far  short  of  extending  to  the  limits  of 
the  earliest  ice  invasion.  In  Illinois  it  fell  short 
about  one  hundred  miles  and  in  Iowa  a still  greater 
distance,  but  projected  into  the  edge  of  the  Drift- 
less Area  in  Wisconsin.  Partly  because  of  this 
development  in  Wisconsin,  Professor  Chamberlin 
has  called  it  the  Wisconsin  Drift  Sheet.  The  lim- 
its of  this  ice  invasion  appear  on  the  small  map  of 
North  America. 

The  southern  border  of  this  drift-sheet  in  Indi- 
ana is  less  conspicuous  than  that  in  the  states  to 
the  east  and  west.  The  ridge  on  its  south-border 
in  Western  Indiana  rises  scarcely  twenty  feet  above 
the  outer  border  tracts,  and  it  is  no  more  conspicu- 
ous in  Central  Indiana.  Indeed,  from  near  Green- 
castle  to  the  vicinity  of  Columbus  there  is  not  a 
well  defined  ridging  of  drift  along  the  border  ; the 
limits  there  being  determined  by  the  concealment 
of  the  loess  beneath  a thin  sheet  of  bowldery  drift. 
From  the  east  border  of  East  White  River  a few 
miles  below  Columbus,  northeastward  to  'White- 
water  valley  at  Alpine  in  Southern  Fayette  county, 
there  is  a sharply  defined  ridge  of  drift  standing 
twenty  to  forty  feet  above  outer  border  tracts. 
Upon  crossing  Whitewater,  where  the  border  leads 
southeastward,  it  is  not  so  well  defined  as  west  of 
the  river,  though  there  is  usually  a ridge  about 
twenty  feet  in  height. 

Although  not  conspicuous  in  Indiana  by  its  re- 
lief, this  border  is  about  as  clearly  defined  as  any- 
where in  the  United  States.  Within  the  space  of 
a half  a dozen  steps  one  will  pass  from  loess-cov- 
ered tracts  of  earlier  drift  to  the  bowldery  drift  of 
this  later  invasion.  Accompanying  the  change 
from  loess  to  bowldery  drift,  there  is  a change  in  the 
color  of  the  soil  from  a pale  yellowish  or  ashy 
color  to  a rich  black.  This  line  is  one  of  great 
agricultural  importance.  The  district  lying  to  the 
north  is  finely  adapted  to  corn  and  timothy,  while 
that  to  the  south  seems  poorly  adapted  to  these 


crops.  The  southern  district  when  uncultivate 
soon  becomes  thickly  covered  with  briers,  a feature 
which  is  not  common  on  the  black  soil  of  tl 
bowldery  drift.  In  this  connection  we  won 
remark,  that  while  the  loess  Juts  usually  great 
fertility,  (he  compact  loess  of  Southeastern  Indian; 
is  adapted  only  to  certain  products.  It  seems  a 
well  adapted  to  wheat,  orchards,  and  small  fruits  a 
the  black  soil,  and  there  appears  to  be  an  apprecia 
tion  on  the  part  of  the  residents  of  this  restricted 
adaptability. 

Between  the  time  when  the  ice-slieet  stood  a 
the  line  just  discussed,  and  the  final  disappearance 
of  the  ice  from  Indiana,  several  moraines  wer 
formed.  The  best  defined  ones  are  indicated  oi 
the  accompanying  State  map.  In  a few  places  not 
indicated  on  the  map,  weak  morainic  lines  hav 
been  observed  but  their  courses  and  connection 
have  not  been  fully  determined. 

These  moraines  indicate  considerable  complex 
. ity  of  movement.  It  will  be  observed  that  several 
'moraines  lead  eastward  from  Illinois  into  Warren 
and  Benton  counties,  Indiana,  and  that  their  east- 
ern ends  are  crossed  by  weaker  morainic  belts  car- 
rying many  bowlders.  These  features  appear  to 
indicate  that  after  the  former  moraines  had  been 
made  and  the  ice  had  retreated  some  distance  nortli- 
j^Avard,  there  was  a readvance  of  ice  from  the  north- 
east to  the  line  marked  by  the  outer  bowlder  belts. 
It  is  as  yet  undecided  whether  much  of  an  interval 
of  deglaciation  preceded  this  advance,  but  there 
was  apparently  a great  shifting  of  ice-movement. 


The  prominent  moraines  which  are  overridden 
in  Benton  and  Warren  counties  mav  find  a con- 


tinuation eastward  in  a belt  of  very  thick  drift 
which  crosses  Central  Indiana  from  Benton  county- 
eastward,  but  which  has  not  the  definite  ridges 
which  are  to  be  seen  from  Benton  county  west- 
ward. This  belt  of  thick  drift  in  Indiana  is  fifteen 
to  thirty  miles  wide,  and  has  a thickness  perhaps 
three  times  as  great  as  the  general  thickness  of 
drift  in  bordering  districts  north  and  south  of  it. 
The  average  thickness  is  fully  200  feet.  It  leads 
south  of  east  across  Tippecanoe  and  Clinton  conn 
ties  to  Western  Tipton  county  where  it  turns 
abruptly  southward  through  Eastern  Boone  and 
Western  Hamilton  counties  and  Marion  county, 
coming  to  White  River  in  the  vicinity  of  Indianap- 
olis. It  there  turns  eastward  and  passes  through 
Hancock,  Henry  and  Northern  Wayne  and  South- 
ern Randolph  counties  into  Ohio.  This  belt  oi 
thick  drift  was  apparently  overridden  by  the  late 
advance.  The  weak  moraines  and  bowlder  belts 
of  the  later  advance  cross  it  obliquely  in  a north 
west  to  southeast  course  in  Western  Indiana,  am 
return  in  a northeastward  course  to  it  in  Henry, 
Wayne,  and  Randolph  counties. 


TOR 


’.1 


This  later  advance  apparently  exten™d  as  far 
| southwest  as  the  bovldery  moraine  of  Central 
.Hendricks  county  and  the  bowldery  morainic  tracts 
of  Southern  Johnson  and  Southern  Shelby  comities. 
|l'  Its  northwest  limits  were  perhaps  at  the  curving 
belt  in  Iroquois  county,  Illinois,  and  Newton  and 
* Jasper  counties,  Indiana,  though  there  was  possi- 
_ bly  only  a reentrant  angle  at  that  line  with  a Lake 
Michigan  ice-lobe  on  the  northwest. 

From  this  outer  limit  of  the  later  advance  the 
ice-sheet  appears  to  have  shrunk  on  all  sides  until 
' its  limits  on  the  northwest  were  at  the  moraine 
which  lies  along  the  north  side  of  the  Wabash  in 
the  vicinity  o{  Logansport,  and  at  the  southwest 
were  near  the  dotted  line  indicated  on  the  Indiana 
map,  leading  from  White  county  southeast  to  the 
vicinity  of  Indianapolis.  It  is  in  the  district 
southwest  of  the  latter  line  that  feeble  moraines 
and  patches  of  bowlders  are  found  crossing  over 
the  great  belt  of  drift  in  oblique  courses.  From 
near  Indianapolis,  the  line  marking  this  later  posi- 
tion of  the  last  invasion,  as  shown  on  the  map, 
leads  eastward  to  the  strong  belt  in  Southeastern 
Delaware  county. 

There  appears  to  have  been  at  the  stage  just 
outlined,  a lake  bordering  the  ice  on  the  northwest 
in  which  the  deposits  of  sand  were  made  which 
form  such  a conspicuous  feature  in  Northwestern 
Indiana  from  Cass  and  White  counties  northwest- 
ward to  the  moraine  north  of  the  Kankakee.  It 
seems  probable  that  the  eastern  and  northern,  as 
well  as  the  southeastern  limits  of  this  lake  were 
determined  by  the  ice,  for  we  find  that  the  sandy 
districts  terminate  at  moraines  on  these  borders. 

The  moraine  leading  northward  from  Northern 
Fulton  county  through  Western  Marshall  and  St. 
Joseph  counties,  would  in  that  case,  be  about  con- 
temporaneous with  the  moraine  on  t he  north  side 
of  the  Wabash  in  Southwestern  Fulton,  Miami, 
Cass,  Carroll  and  White  counties,  and  both  would 
be  of  about  the  same  date  as  the  strong  moraine 
lying  north  of  the  Kankakee.  These  correlations 
are  not,  however,  fully  established  and  should  be 
taken  simply  as  a working  hypothesis  to  be  tested 
by  future  developments  in  the  study  of  t hat  region. 

In  Northeastern  Indiana,  moraines  appear  along 
the  north  border  of  the  Mississinewa,  Salamonie, 
Wabash  and  St.  Mary’s  rivers,  which  were  appar- 
ently formed  in  succession  as  the  ice  was  wasting 
away  after  its  last  advance.  These  moraines  are 
traceable  eastward  across  Northern  Ohio  and  north- 
eastward into  Southeastern  Michigan  and  mark 
successive  limits  of  a lobe  of  ice  which  flowed 
south  westward  across  the  Erie  and  Maumee  basins. 
This  ice-lobe  appears  to  have  persisted  at  the  line 
of  the  outer  of  these  four  belts  to  a date  wlven 
there  was  open  country  on  the  northwest,  for  the 


drainage  lines  lead  from  this  morainic  belt  north- 
west to  the  St.  Joseph  river,  passing  across  the 
moraines  of  the  intervening  district,  as  they  would 
scarcely  have  done  had  the, ice  persisted  there  as 
long  as  in  the  Erie  lobe.* 

Having  traced  the  ice-sheet  to  its  final  disappear- 
ance from  Indiana,  the  reader  may  find  in  Mr. 
Taylor’s  History  of  the  Great  Lakes  a continuation 
of  the  events  incident  to  the  retreat  of  the  ice  to- 
ward Labrador  f. 

SUCCESSION  OF  ICE  INVASIONS  SHOWN  BY  DRIFT 

> DEPOSITS. 

The  evidence  of  difference  in  the  age  of  the  drift, 
shown  by  erosion  of  its  surface,  has  been  discussed. 
Other  lines  of  evidence  of  successive  invasions  have 
been  recognized.  One  of  the  most  interesting  and 
significant  is  the  presence  in  a vertical  section  of 
sheets  of  drift  showing  differences  of  age  and  of 
derivation.  Such  sections  are  occasionally  seen 
along  streams,  and  are  frequently  brought  to  light 
by  wells.  Professor  Chamberlin  has  presented  as 
the  frontispiece  illustration  in  Geikie’s  last  edition 
of  “The  Great  Ice  Age,”  such  a section  found  on 
Stone  creek  near  Williamsport  in  Warren  county, 
Indiana.  There  is  exposed  at  the  base,  a reddish  till 
of  the  earliest  drift  upon  which  there  rests  a bed  of 
old  ferruginous  gravel.  This  gravel  is  overlain  by 
a fresh  blue  till,  which  is  apparently  of  the  age  of 
the  moraines  which  lead  into  that  county  from 
the  west.  Above  this  till  is  another  gravel  bed 
much  fresher  than  the  one  below.  Above  the 
gravel  is  a gray  till,  which  was  apparently  deposited 
by  the  ice  at  the  time  when  it  fronted  southwest, 
and  had  its  terminus  at  the  bowlder  belt  which 
crosses  Warren  county  from  north  to  south  just 
west  of  the  place  where  this  section  is  exposed. 

SUCCESSION  OF  ICE  INVASIONS  SHOWN  BY  ST  RLE. 

The  strite  of  Western  Indiana,  as  may  be  seen  by 
the  maps,  are  widely  different  in  their  bearings. 
Until  the  several  ice  invasions  had  been  recognized 
they  were  a puzzling  feature;  but  they  are  now 
found  to  support  the  other  lines  of  evidence  of  such 
invasions.  Perhaps  the  best  illustration  is  to  be 
found  near  Williamsport.  There  are  found  in  this 
village  two  sets  of  strife ; one  bearing  southeast 
and  belonging  apparently  to  the  earliest  invasion  ; 
another  bearing  southward  and  belonging  appar- 
ently to  the  same  invasion  which  formed  the  bulky 
moraines  in  that  vicinity.  Two  miles  east  of 
Williamsport,  on  the  north  side  of  the  Wabash, 
Professor  Chamberlin  found  a third  set  of  striae, 
with  westward-bearing,  which  apparently  pertain 
to  the  last  invasion  of  the  ice. 

At  Monon  and  near  Kentland,  strife  pf  two  dis- 

*See  18th  Report  Incl.  State  Geologist,  pp.  29,  89. 

Inland  Educator,  Vol.  II.  p.  uts,  2l(>. 


32 


The, 


tinct  sets  appear.  The  latest  bear  westward  and 
belong,  apparently,  to  the  last  ice  invasion.  The 
date  of  the  earlier,  southward-bearing  striae,  is  as 
yet  undetermined. 

THICKNESS  OF  THE  DRIFT. 

There  are  surprising  differences  in  the  thickness 
of  the  drift  within  the  state.  The  portion  of  the 
older  drift  exposed  to  view  has,  as  already  noted, 
an  average  thickness  of  about  thirty  feet.  The 
additional  100  feet  of  the  newer  drift  is,  however, 
deposited  very  irregularly.  In  the  beltof  thick  drift 
which  leads  from  Benton  county  southeast  to 
Marion  county,  and  thence  east  into  Ohio,  the 
thickness  is  probably  200  feet.  The  portion  of  the 
newer  drift  area  to  the  south  of  this  belt  has  an 
average  of  about  fifty  to  seventy-five  feet.  A still 
larger  tract  extending  north  from  this  belt  of  thick 
drift  as  far  as  Allen  county  and  the  west-flowing 
portion  of  the  Wabash,  has  only  fifty  to  seventy- 
five  feet  with  limited  areas  where  its  thickness 
is  but  twenty  to  thirty  feet.  In  Northwestern 
White,  Southwestern  Pulaski,  and  Southern  Jas- 
per counties  there  are  several  townships  in  which 
scarcely  any  drift  appears  excepting  bowlders 
and  sandy  deposits.  In  Northern  Indiana  the  drift 
is  very  thick.  Its  average  thickness  for  fifty  miles 
south  of  the  north  boundary  of  the  state  is  prob- 
ably not  less  than  250  feet,  and  may  exceed  300 
feet.  At  Kendallville  it  is  485  feet,  and  at  several 
cities  on  the  moraine  which  leads  northeast  from 
Fulton  county  to  Steuben  county,  its  thickness  has 
been  shown  by  gas  borings  to  exceed  300  feet. 
The  rock  is  seldom  reached  in  that  region  at  less 
than  200  feet.  Were  the  drift  to  be  stripped  from 
the  northern  portion  of  Indiana  its  altitude  would 
be  about  as  low  as  the  surface  of  Lake  Michigan, 
though  much  of  the  present  surface  is  200  to  300 
feet  above  the  lake. 

Denmark,  Iowa. 


Method  in  Arithmetic.— XII. 

Typical  Plans — Finding  the  Area  of  a Circle. 


fhe  area  of  a circle  is  found  by  multi- 
plying the  diameter  sepia  red  by  .7854. 

3.  The  area  of  a circle  is  found  by  multi- 
plying the  scpiare  of  the  radius  by  3. 14  hi. 
The  first  is  chosen  as  the  form  to  be  learned  in 
this  lesson.  The  book  definition  need  not  be 
studied  antecedently  to  the  lesson.  The  truth  is 
to  be  developed  from  the  nature  of  the  triangle 
and  the  circle  and  their  relations  to  each  other. 

II.  Purposes  in  the  mind  of  the  teacher ; effects 

upon  the  minds  of  the  pupils. 

1.  To  give  the  pupils  a knowledge  of  the 
subject  matter,  that  the  circle’s  area  may 
be  found  by  multiplying  the  circumfer- 
ence by  one-half  the  radius. 

2.  To  arouse  pleasurable  emotions  in  this 
search  for  and  mastery  of  new  truths. 

3.  To  affect  the  will  in  the  entire  process 
for  immediate  and  remote  results. 

III.  Movements  of  mind  in  learning  this  new 
truth. 

1.  Rethinking  a particular  triangle. 

a.  Its  form  and  parts. 

b.  Its  area  as  equalling  the  product  of 
one-half  its  altitude  by  its  base, 
which  is  easily  generalized. 

2.  Rethinking  a particular  circle, 
a.  Its  form  and  parts. 

3.  Thinking  this  circle  as  made  up  of  sev- 
eral triangles  whose  bases  are  equal. 

a.  The  sum  of  whose  bases  equals  the 
circumference. 

b.  Whose  altitudes  equal  the  radius. 

4.  Thinking  the  area  of  the  circle  is  equal 
to  the  sum  of  the  areas  of  the  triangles, 
and  is  the  product  of  the  circumference 
by  one-half  the  radius. 

5.  Thinking  this  process  as  general,  the 
area  of  any  circle  may  be  so  found. 

6.  The  association  of  the  particular  and 
general  until  the  truth  is  fixed,  the  sub- 
ject matter  is  a possession  of  the  pupil. 


Mensuration  should  be  one  line  of  work  in  the 
grades  of  a well-organized  school. 

The  relations  of  number  and  form,  of  arithmetic 
and  geometry,  should  be  kept  in  mind  by  the 
teacher  and  progressively  learned  by  the  pupil. 

To  illustrate  the  general  work  in  teaching  such 
relations  the  following  is  given,  a relation  between 
the  triangle  and  the  circle  : 

I.  The  general  subject-matter  is  the  process  of 
finding  the  area  of  a circle.  This  may  be 
one  of  several  processes. 

1.  The  area  of  the  circle  is  found  by  mul- 
tiplying the  circumference  by  one-half 
the  radius. 


IV.  Basis  for  this  work,  the  known  whence  the 

process  advances. 

1.  A knowledge  of  the  triangle,  its  parts, 
and  the  process  for  finding  its  area. 

2.  A knowledge  of  the  circle  and  its  parts, 
at  least  the  circumference  and  radius. 

3.  Some  experience  in  working  out  similar 
ideas. 

Y.  Devices  or  means  used  in  the  process  of  teach- 
ing this  particular  subject. 

1.  A triangle,  to  cause  the  rethinking  of  its 
parts  and  their  relation  to  the  area. 

2.  A circle  cut  into  any  number  of  equal 
triangles.  To  lead  to  thinking  the  equiv- 


V 


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